1. Technical Field
The invention relates to the performance enhancement of network browsers in a computer environment. More particularly, the invention relates to the intelligent prefetching of documents across a computer network, efficiently using the free bandwidth and enhancing perceived performance on the client.
2. Description of the Prior Art
The popularity of the Internet has exploded in recent years. Typical users are based in their homes with Internet access through modems. Unfortunately, modem access speeds are relatively slow, causing Internet browsers to respond sluggishly. Slow servers and networks also contribute to this latency. The latency on the client is measured by the time lag that is perceived by the user. It is the time period from the moment that the user first clicks on a document link to the point in time when the document actually appears on his screen.
When the user clicks on a particular link, the Internet browser pulls a web document off of a web site. The browser does this by instantiating a connection with the web site server and pulls the document down from the server.
One approach to improving the perceived performance of the browser is by prefetching documents. Prefetching is the retrieval of documents from the web before the user makes an explicit request for them. The links are pulled down from the server onto the client and placed in a cache on the client. When the user actually clicks on a link, it comes from the cache rather than the network. The perceived performance is increased because the user thinks that the document is coming off the network when it actually is coming from his cache.
Many Internet browsers and add-on programs currently perform a "blind" prefetch, whereupon the browser pulls down all of the document links on a web page before the user has actually clicked on them. For example, in a very simple model of blind prefetching, the client pulls down page A from a server, parses the document links on that page and pulls each of them into the local cache. When the user clicks on a link to page B, it is loaded from the prefetched copy in the cache.
One of the problems with the blind prefetch approach is that it is very inefficient. The client must make multiple requests for all of the document links on a page. The server must respond to each request by sending the appropriate document, thereby forcing the server to send many more documents than are needed. This scenario is repeated for every client communicating with the server. The result is high network traffic and overloading of the server. Further, the client has no control over what is being pulled down from the server in this approach; it blindly makes the requests.
It would be advantageous to provide a prefetching and control system that improves the user-perceived network performance by allowing the client to efficiently decide what documents to prefetch, thereby reducing the demand on the server and network. It would further be advantageous to provide a prefetching and control system that enables the server to designate to the client what document links are important or the most common on a page.